Need help!

Me and my boyfriend are each other's first and we have been having protected sex lately and withdrawl. But a couple days ago he went in without a condom for like 7 seconds then he took it out and put the condom on and we continued. Then he pulled out when he finished. What r the changes of me being pregnant? (We r 16,17 and trying to get me on the BCP) my % on glow was 3%